This step is special for you who have your own xml template or just wanna try the non-default blogger templates. if you don't have any, you can download them freely on internet; open google.com => type "free blogger xml template" as the keywords => you will find many results :)
Usually, the xml templates that provided freely in internet has a fresh view on it's layout, Even though we can apply this view on blogger default template, we still need a long time and good effort to accomplish it. So, downloading it in internet freely was the better option...
Well, let's talk more about uploading xml template in blogger...
to upload XML template in blogger, follow the steps below:
1. Go to your blogger account
2. Choose "template" option
3. Look at the top right of the page => Click "backup/restore" button
4. Warning! to be aware of an error in uploading the xml template you have to backup your full template by clicking "download full template" button. With this action, you can reupload your previous template if some error occured
if you are done with downloading, now you can continue to upload your xml template
5. Click "browse..." button => Choose your xml template on your hard drive
6. If some notification appeared, just choose "keep widget" (you may delete the widget later manually)
7. Click upload and finish!
Enjoy your xml template